Abstract
The CARA program has been running since 2008 by the French reference laboratory for air quality monitoring (LCSQA) and the regional monitoring networks, to gain better knowledge—at a national level—on particulate matter (PM) chemistry and its diverse origins in urban environments. It results in strong collaborations with international-level academic partners for state-of-the-art, straightforward, and robust results and methodologies within operational air quality stakeholders (and subsequently, decision makers). Here, we illustrate some of the main outputs obtained over the last decade, thanks to this program, regarding methodological aspects (both in terms of measurement techniques and data treatment procedures) as well as acquired knowledge on the predominant PM sources. Offline and online methods are used following well-suited quality assurance and quality control procedures, notably including inter-laboratory comparison exercises. Source apportionment studies are conducted using various receptor modeling approaches. Overall, the results presented herewith underline the major influences of residential wood burning (during the cold period) and road transport emissions (exhaust and non-exhaust ones, all throughout the year), as well as substantial contributions of mineral dust and primary biogenic particles (mostly during the warm period). Long-range transport phenomena, e.g., advection of secondary inorganic aerosols from the European continental sector and of Saharan dust into the French West Indies, are also discussed in this paper. Finally, we briefly address the use of stable isotope measurements (δ15N) and of various organic molecular markers for a better understanding of the origins of ammonium and of the different organic aerosol fractions, respectively.
Highlights
Due to their adverse health effects, and their environmental, economic, and climatic impacts, airborne particles are the subject of great concern within the scientific community [1,2,3,4,5,6]
LCSQA and IGE organized an inter-laboratory comparison (ILC) dedicated to the measurement of this compound and its Levoglucosan is known as a tracer for biomass burning aerosols [58], and has been widely used to estimate the concentration of organic matter related to this emission source by applying a multiplicative conversion factor [59]
Outcomes of this study notably indicate a homogeneous spatial distribution of the Saharan dust loadings during PM10 concentration peaks and confirm the major role played by natural particles (Saharan dust, and relatively high sea salt background levels) onto air quality over the island
Summary
Due to their adverse health effects, and their environmental, economic, and climatic impacts, airborne particles are the subject of great concern within the scientific community [1,2,3,4,5,6]. The contribution of these species to PM2.5 shall be monitored at a few remote stations of EU member states—with no fixed limit nor target value as yet—according to directive 2008/50/CE (1 site per 100,000 km in each country) This requirement has been elaborated to better assess transboundary air pollution phenomena, complementary to the co-operative program of the long-range transmission of air pollutants in Europe, known as the European Monitoring and Evaluation Programme (EMEP, www.emep.int, [9,10]), under the Convention on Long-Range Transboundary Air Pollution (CLRTAP). These initiatives are still mainly focused on background air pollution at a regional (or larger) scale, rather than on hotspots for population exposure to poor air quality (i.e., urban and/or heavily industrialized areas) In this context, LCSQA has been implementing, together with the MTE and AASQAs, an ambitious operational network for in situ observation of urban PM chemical composition and sources (the CARA program, www.lcsqa.org/fr/le-dispositif-cara) since 2008 [13], with the following objectives:. These remaining filter parts are saved in freezers, with non-analyzed filters, contributing to enlarge the wide sets of PM10 samples that can be made available for possible further analyses (e.g., for oxidative potential measurements [25], or investigation of the links between PM chemistry and microbiology, [26])
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